.ProseMirror p.is-editor-empty:first-child::before {
    content: attr(data-placeholder);
    float: left;
    color: #adb5bd;
    pointer-events: none;
    height: 0;
}
.mention {
    background-color: #E0DDFC;
    border-radius: 4px;
    padding: 2px 4px;
}